Thursday, 8 November 2012

Lining Out

200 metres of oak, and 1200 metres of 150mm x 15mm bead and butt (tongue and groove with a bead) were delivered to the road side.  Some big tides were due so it was imperative to get it moved before it moved itself.


 This is only part of the load.  I got into a routine and propped ten lengths against the hull, climbed up and fed it down the hatch.  I then went below and put it into stick in the cabin.


 

 Before any of it was put up the back faces were coated in ullage.  My special brew of wood preserver and varnish.  It penetrated quite well and sealed the wood.  I hear some folk use Thomsons water seal too.  I used Blackfriars preserver because it dried faster and smelt less than Cuprinol.




I started in the middle of the underneath of the cabin top and worked outwards.  I know some of you will not like all this pine.  Too much, feels like a sauna.  Some folk us oak boards instead, some use flat sheets of veneered ply.  Some people even use plasterboard.




This is the bow section, notice the cabling for the electrics is being put in at this stage.  Much easier now than later.  All the electrical services run in ducts underneath the side deck.







Here is the wall in the heads (bathroom remember).  Very strong and simple, the planks are screwed to each of the battens or cross members.  Two screws to each plank at each intersection.  Notice how we covered the window openings and cut them out later after fixing.  This stops creep and keeps things lined up nicely.



The other side with a nice fire going with the offcuts.

 

 A close up of the fire stop round the chimney where it goes through the roof.  There is a steel tube through the cabin top, this has lugs welded on the bottom to take the weight of the double stainless steel chimney.  There is also a flange of alluminium round the opening and the wood is cut to this.



 
 This is what it starts to look like when a couple of coats of Chinese wood (tung) oil have been applied.  With age the wood has darkened from that white new pine to a rather gorgeous orangey brown.  Well I like it anyway.


 Here we have the aft cabin, the pipes on the right are the hydraulic lines for the steering.


There is a fair curve here and it was not possible to bend the wood round all of it.  The tighter sections had to be straightened.

 




 Here we see the window panels cut out and trimmed.  Covering strips matching the other trims are used to hide vertical joins and corners.

Insulation time.

After what seemed like months of work, well actually it was, the time had come to insulate.  It was a slight rush as I had booked the team and there was still loads to do.  The thing is with sprayed foam insulation is it goes everywhere.  So whatever you don't want foamed you have to cover with tape and plastic.  All the faces of the battens are covered in parcel tape leaving suitable tags for a gloved hand to pull it off.  Plastic was used in the bilge areas, windows and such like.

 






 It is only necessary to foam down to the waterline or a little below.  The warmish waters of temperate climates will insulate the bottom.  In more northern waters it will be preferable to insulate the entire hull.  The only other time you may wish to insulate the bilge area is if your mooring dries out and there is no water around to insulate.





I used Websters and found the crew rather good.  Get a firm to spray and cut back.  There will always be an amount of cut back.  Where the foam is over applied and is too thick.  If the crew have to cut back then they will be more careful in the spraying.  Ventilate the boat for a day or two to get rid of the chemicals coming out of that foam.


 The foam is in two parts, mixed at the spray nozzle which needs to be about two feet from the surface.  It is sometimes difficult to get "behind" things like angled steel returns.  You can see in the above photo some uneven beads of foam next to the curved frames.  I used the professional spray foam in cans to work into the shy places.  I did this on all the frames and in a few other awkward to get at places.  You can see there is no foam on the from edges of the battens.  When the foam has been sprayed the tape is pulled off together with any overspray.  Any foam above the level of the battens is cut back using a rip saw used on its side.  Just like taking  slice from and uncut loaf!


Battening out the inside.

 There was one last thing  to do before painting the inside and yes I forgot and had to repaint some bits.  It has suffered rather badly when I was welding on the outside.  But hey, no-one's perfect.  Rubbing strakes, that's what I forgot.  Those bits of steel that take the knocks instead of your lovely hull paint.  Why didn't I get the builder to do this for me?  Well I wasn't sure where I wanted them and he didn't seem to know either.  I did try having them diagonally like the commercial vessels have them but this was rather fussy.  In the end I went for an extra two in-between the top and bottom ones already there.  Lengths of D section were welded together and dogged to the hull for continuous welding.  Dogged - scraps of shaped steel tacked to the hull for support and enable a metal wedge to be knocked in and keep the rubbing strake close to the hull for welding.




Of course the other things were the air intakes for the engine room, this is actually the air out, the intake is on the other side.


This is the inside and shows the hole into the engine room which will have a 24v Kenlowe fan. There is a baffle to allow water runoff and a top lid for access.


These are the permanent boarding steps as required.


There, that's better, now we can get on with undamaged paint inside!


So the inside was painted with zinc rich primer.  Actually a lot of it was sprayed with a HVLP spray system.  Cheap but very effective.  But I did use brush and roller too.  There was a holding primer on all the steelwork so after a clean it was on with the paint.  I alternated between red and grey so as I could make sure everything was covered properly.  In the middle of this battens were bolted to the frames of the vessel.  These frames are every 600mm and are used to attach the boat interior, walls, linnings etc.

 

I used 50mm x 50mm (2" x 2") for the floor and 50mm x 25mm (2" x 1") for the sides and ceiling.  I am using the word ceiling to mean the inside of the roof or cabin not in the true "boat"  sense.  I used douglas fir as I had loads of it.  It was treated with Cuprinol and luted and bolted to the frames.  For luting, I used Sikaflex 291, ok it's not a traditional luting but I reckon its fine.  What we are trying to do is make a barrier between the wood and the steel to avoid poltice corrosion and damp.

 

The insulation on this boat is sprayed foam.  They do say that the foam itself will protect the steel even unpainted.  This assumes the foam: a - covers all the steel and b - sticks to it properly.  This I could not be sure of and I wanted to try and make sure that I was not going to have to fix things later on.  Hence the, some would say, extreme paint system on the inside.  I is a well known fact that boats rust from the inside out.

 

You can see in the above photo that pre-painted battens are ready to be put up.

1 blast primer, 4 x zinc rich primer, 1 x undercoat (white), 2 x topcoat (white).  Traditional colours for bilges seems to be grey or red.  These are not good colours for picking up defects in a steel boat.  If there is any rust then I want it to stick out straight away.  White encourages you to keep it clean too.  It doesn't matter really what colour you use when it's going to be hidden behind the foam insulation.

 

I used galvanised countersunk bolts, nuts and penny washers for attaching the  battens.  I could have used stainless but they were all going to be oversprayed so I didn't think it would be worth it.  The cost difference in minimal really.

 

Spraying in a confined space is not to be recommended unless you have a decent mask and good ventilation.
 

 I had an axial flow fan mounted in a frame that would fit over the fore or aft hatch.  The air flow from that beasty would suck you had off.  

Tuesday, 6 March 2012

A few more holes.

The weed hatch over the propeller is large but strong and has a well bolted flange rather than a quick release.




The box cooler for the engine cooling was another huge hole.



Note the stress relievers welded on the corners to mitigate the stress on the corners in the hull cut out.  The tube stack is withdrawn through the cut out in the bulkhead on the right.  The cooler box cut through a frame so the cut frame ends were fully welded to the sides of the box.

 The tube for the bow thruster was fully welded inside and out but left long for fairing.  First the ends were heated and belled over using oxy-propane and a large adjustable spanner and big hammer.


Patterns were made for the cone sections and transferred to the steel.

 
These were then cut and bent to the hull shape.




And the reason for all this fuss?  Thrusters work so much better with a smooth flow.  So with radiused and flat ends the water enters without turbulence and the efficiency is increased and the bag of nails noise significantly reduced.  Thrusters work by sucking the boat rather than just pushing hence the need for a good smooth intake.

There is another hole to be seen in the photo above the thruster tube.  The drain for the gas locker.  This is supposed to be a certain size (according to a formula) to let the gas out rather than just be a drain for any water that gets in.  So apart from a few holes for filler pipes and water drains and vents, eleven I think, that's it for the holes and none below the waterline.

Sunday, 12 February 2012

Tanks and things.

One of the tasks was to make and fit 6 extra inspection hatches into the tanks under the floor.  They came with just one in the middle.  No good as the sections beyond the baffles could not be reached.  One does wonder how many tanks there are running around without paint and full of build debris!

To save buying extra steel I made the hatches of a size that meant that the window cut outs could be used.  At the same time as the hatches were fitted I also organised the pipe fittings for the tanks.  Tank No 1 is 1000 litres and is for water, tank No 2 is also for water and is 750 litres and tank No 3 is 600 litres and is for the black water.  Black water is a pretty name for sewage.  Not all of the large tank fittings would fit under the floor and I was keen not to have them on the sides in case of leaks.  I made up some recessed cups and welded them in.

The tanks were cleaned up and primed and finished in tank black which is suitable potable water.  Handles were bent up and welded on.  I fitted my hatches by welding the bolts to the hatch and feeding the hatch through the opening, the holding bolts then protrude through holes drilled in the tank.  The hatches were bedded on a neoprene seal.  I used a polyurethane sealant on the black tank lids but made it undo-able by using some clingfilm to stop it sticking whilst it went off, then it was nipped up after.




I should really have radiused the corners of the tank cut outs to combat stress cracking but the tanks should not be too stressed hopefully.





During this tank time work carried on in the paint department.  The high build zinc primers changed from red to grey a couple of times and after and undercoat was finished in white gloss. I love white bilges me.


The paint wouldn't dry in the tanks and it took me a while to figure it out.  I had assumed it was the cold but it wasn't that cold.  The solvent driers coming off the paint are heavier than air and stayed inside tank.  I had to use a fan and flexible hose to suck the vapour out.  Yes it was ignition protected so we didn't blow up.